Research​

Our lab has diverse interests in avian evolution. A common theme is how the ecology and behavior of birds influences evolutionary dynamics, such as the process of speciation, the evolution of geographic range, and the adaptation of birds to global climate change past and present. Our research is field-, lab- and specimen-based, both leveraging and contributing to the scientific capacity of museum research collections.​​Explore some of our ongoing projects below:

The influence of seasonal migration on population differentiation in boreal birds

Migratory birds move rapidly across large areas of the earth, suggesting that they have high capacity for dispersal throughout their ranges. Yet, many lineages of migratory birds are known to have diversified rapidly, indicating that the high vagility of migrants does not prevent speciation. Such rapid diversification despite an elevated potential for gene exchange presents an evolutionary paradox that has received little attention. We are performing a comparative phylogeographic project on over 30 species of boreal forest North American birds to test how migration and dispersal are related, and how these movements influence population differentiation and ultimately speciation. Our research will also inform historical questions such as the history of the North American boreal avifauna, as well as contemporary topics such as the population connectivity and conservation genetics of migratory birds.

Comparative genomics of speciation and community assembly in tropical montane birds

We are interested in furthering understanding of mutation-order speciation (speciation that is not caused by divergent ecological selection pressures) and determining how important it is for avian diversification. Birds of tropical montane regions — with their incredible diversity of color patterns — will continue to serve as a model system for our research questions, which include: How much genomic and phenotypic divergence is required for sister species in secondary contact to coexist without exchanging genes? Conversely, how much gene flow between incipient species will prevent their phenotypic differentiation? How does the degree of ecological difference between populations contribute to the tempo of genetic and phenotypic divergence, and their likelihood of achieving sympatry? Is reinforcing selection against hybrids broadly important for the completion of avian speciation and achievement of secondary sympatry, or simply for the maintenance of hybrid zones? This research involves comparative genomics, fieldwork in the Andes and elsewhere in the tropics, and studies of museum specimens.

Geographic range evolution in migratory birds

The seasonal migrations of birds and other animals have long captured human imagination, but our understanding of why species migrate to particular places remains poor. For example, many closely related species of songbirds breed alongside one another in the boreal forests of North America. Yet each fall these species migrate to distinct, often non-overlapping winter ranges — some species to the rainforest of the Amazon, others to Caribbean islands, others no further south than the southern United States — only to return each spring to the same patch of coniferous forest. Why do closely related species with overlapping ranges in one season have such different ranges in other seasons? And if an individual species can exist in such diverse habitats as spruce-fir forest and Amazonian jungle, why would its distribution be limited to only these disparate biomes? These idiosyncratic distributions challenge our understanding of the factors that limit species’ geographic ranges, and complicate our ability to predict how species will adapt to climate change and environmental degradation. We are using phylogenetic comparative methods combined with large scale distributional and ecological datasets to investigate the mystery of migratory bird distributions.

​Through the dedicated work of museum curators, staff, volunteers and supporters, natural history collections harbor an unparalleled record of biodiversity during an era of rapid anthropogenically driven global warming and habitat degradation. We are leveraging museum collections of North American migratory birds collected over the course of the last century to understand rapid changes in avian morphology, ecology and population size and structure. Our current focus is on understanding patterns of rapid morphological evolution we observe in time series of specimens of Nearctic-Neotropical migratory birds that were salvaged from window collisions in Midwestern cities.